Cross-Track Constant Velocity Joint for Large-Angle Force Balance
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Solution Overview
Problem
Fixed type constant velocity universal joints with maximum operating angles greater than 50° face issues such as ball loss of contact, disturbance in force balance, reduced constant velocity characteristics, transmission efficiency, and durability due to shorter track grooves and increased load on specific balls, leading to potential damage and noise generation.
Innovation Solution
A cross track groove type design where the outer joint member's track grooves have arc-shaped portions with no axial offset and opposite inclination directions, and the inner joint member's track grooves are mirror-symmetric, allowing balls to maintain contact and balance forces even at large operating angles, preventing ball drop-off and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the outer joint member length is shortened to prevent interference with the intermediate shaft, then interference is avoided, but the track grooves become shorter causing balls to lose contact
Solution Approach 1:
The patent applies dimensionality change by forming the track groove with an arc-shaped portion having a curvature center offset in the axial direction, rather than using a conventional straight or simple curved groove. This axial offset creates additional radial space that allows the ball to maintain contact with the track groove even when the outer joint member length is reduced, thereby resolving the contradiction between preventing interference and maintaining ball contact reliability
Solution Approach 2:
The patent changes the geometric parameters of the track groove by introducing an arc-shaped portion with a specific curvature center offset in the axial direction. This parameter modification allows the track groove to accommodate the ball's movement trajectory at large operating angles while maintaining contact, enabling the outer joint member to be shortened without causing ball drop-off
2Object-affected harmful factors
If the track groove length is reduced due to shorter outer joint member, then interference is prevented, but force balance is disturbed and durability decreases
Solution Approach 1:
By offsetting the curvature center of the arc-shaped track groove portion in the axial direction, the patent creates a three-dimensional groove geometry that maintains effective ball contact length despite the reduced outer joint member length. This axial dimension adjustment preserves force balance and durability while preventing interference with the intermediate shaft
Solution Approach 2:
The patent employs spherical curvature in the arc-shaped track groove portion with a curvature center offset in the axial direction. This curved geometry better matches the ball's contact trajectory at large operating angles, ensuring continuous contact and balanced force distribution, thereby maintaining strength and durability without requiring a longer outer joint member
3Adaptability or versatility
If the operating angle is increased beyond 50°, then turning performance improves, but ball contact is lost and noise increases
Solution Approach 1:
The axial offset of the curvature center in the arc-shaped track groove creates additional contact space that accommodates the ball's movement at large operating angles. This dimensional adjustment allows the joint to operate reliably beyond 50° without ball drop-off or noise generation
Solution Approach 2:
The arc-shaped track groove with spherical curvature centered at an offset position provides a contact surface that follows the ball's trajectory at large operating angles. This curved geometry ensures continuous smooth contact, preventing noise and maintaining reliable operation at operating angles exceeding 50°
Data Source
AI summary
A fixed type constant velocity universal joint has outer joint member track grooves each with a raceway center line that includes an arc-shaped portion having a curvature center that has no offset with respect to a joint center in an axial direction. The track grooves are formed such that adjacent track grooves are inclined in opposite directions. The joint also has inner joint member track grooves that are each formed to be mirror-symmetric with a corresponding one of the outer joint member track grooves with a plane including the joint center and being orthogonal to the axis of the joint at an operating angle of 0°. When at a large operating angle, an operating angle at which a torque transmission ball loses contact with the inner joint member track groove is larger than that at which the torque transmission ball loses contact with the outer joint member track groove.